Synergistic effect of elevated temperature, pCO2 and nutrients on marine biofilm

• Response of marine biofilm community to warming and acidification in varying nutrients
• Warming reduced phytoperiphytic biomass but enhanced biofilm bacterial biomass in unenriched condition.
• Acidification enhanced phytoperiphytic biomass but reduced biofilm bacterial biomass in unenriched condition.
• Warming and acidification in synergy led to lowest periphytic biomass in unenriched condition.
• Nutrient enrichment led to higher periphytic biomass in the biofilm.

Natural marine biofilms provide signatures of the events that occur over a period of time and can be used as bioindicators of environmental changes. Hence, the effects of temperature (30 and 34 °C), pCO2 (400 and 1500 μatm) and nutrients (unenriched and enriched f/2 media) on the marine biofilm were evaluated using a 2 × 2 × 2 factorial design. In unenriched condition, acidification significantly increased the abundance of phytoperiphytes whereas reduced that of bacteria and it was vice versa in the enriched condition. Warming had significant negative effect on the abundance of both phytoperiphytes and bacteria, except in unenriched condition wherein it favoured bacterial growth. Synergistically, acidification and warming had deleterious effects resulting in further reduction in the abundance of both phytoperiphytes and bacteria, except in enriched condition wherein bacterial abundance increased. Such changes in biofilm communities in response to warming and acidification can have cascading effect on the subsequent build-up of macrofouling community.